#![cfg(not(windows))]
use std::mem;
use crate::timer::CPUTimes;
use crate::util::units::Second;
#[derive(Debug, Copy, Clone)]
pub struct CPUInterval {
pub user: Second,
pub system: Second,
}
pub struct CPUTimer {
start_cpu: CPUTimes,
}
impl CPUTimer {
pub fn start() -> Self {
CPUTimer {
start_cpu: get_cpu_times(),
}
}
pub fn stop(&self) -> (Second, Second) {
let end_cpu = get_cpu_times();
let cpu_interval = cpu_time_interval(&self.start_cpu, &end_cpu);
(cpu_interval.user, cpu_interval.system)
}
}
fn get_cpu_times() -> CPUTimes {
use libc::{getrusage, rusage, RUSAGE_CHILDREN};
let result: rusage = unsafe {
let mut buf = mem::zeroed();
let success = getrusage(RUSAGE_CHILDREN, &mut buf);
assert_eq!(0, success);
buf
};
const MICROSEC_PER_SEC: i64 = 1000 * 1000;
#[allow(clippy::useless_conversion)]
CPUTimes {
user_usec: i64::from(result.ru_utime.tv_sec) * MICROSEC_PER_SEC
+ i64::from(result.ru_utime.tv_usec),
system_usec: i64::from(result.ru_stime.tv_sec) * MICROSEC_PER_SEC
+ i64::from(result.ru_stime.tv_usec),
}
}
fn cpu_time_interval(start: &CPUTimes, end: &CPUTimes) -> CPUInterval {
CPUInterval {
user: ((end.user_usec - start.user_usec) as f64) * 1e-6,
system: ((end.system_usec - start.system_usec) as f64) * 1e-6,
}
}
#[cfg(test)]
use approx::assert_relative_eq;
#[test]
fn test_cpu_time_interval() {
let t_a = CPUTimes {
user_usec: 12345,
system_usec: 54321,
};
let t_b = CPUTimes {
user_usec: 20000,
system_usec: 70000,
};
let t_zero = cpu_time_interval(&t_a, &t_a);
assert!(t_zero.user.abs() < f64::EPSILON);
assert!(t_zero.system.abs() < f64::EPSILON);
let t_ab = cpu_time_interval(&t_a, &t_b);
assert_relative_eq!(0.007655, t_ab.user);
assert_relative_eq!(0.015679, t_ab.system);
let t_ba = cpu_time_interval(&t_b, &t_a);
assert_relative_eq!(-0.007655, t_ba.user);
assert_relative_eq!(-0.015679, t_ba.system);
}